In this work, the interaction of protonated amino acids with a chromene bearing a fused 18-crown-6 ether moiety was studied by UV–vis and NMR spectroscopy. Initial closed forms of the chromene form monotopic 1 : 1 complexes, the ammonium group being localized inside the crown ether cavity. UV-irradiation leads to transformation of the ring-closed species into the ring-opened form. Depending on the amino acid length, either ditopic or monotopic 1 : 1 complexes are formed. Such complexes are stabilized by the additional H-bonding between the carboxylic group of the acid and the carbonyl oxygen atom of the ring-opened form. Cessation of the irradiation results in ring-closure to the chromene with concomitant change of the complexation mode.
在本研究中,通过紫外-可见光谱和核磁共振(NMR)光谱技术,探究了质子化
氨基酸与一种含稠合18-
冠醚基团的苯并
吡喃类化合物之间的相互作用。初始的环闭形式苯并
吡喃形成了单点1:1的复合物,其中
铵基团定位在
冠醚腔内。紫外光照促使环闭物种转变为环开形式。根据
氨基酸的长度,会形成双点或单点的1:1复合物。这些复合物通过酸的羧基与环开形式的羰基氧原子之间额外的氢键得到稳定。停止光照后,会发生环闭合,苯并
吡喃同时伴随复合模式的改变。